Republicans have grown increasingly worried about losing control of the Senate, as President Trump’s approval rating tumbles and Democrats gain steam in key battleground races.

Senate Majority Leader Mitch McConnell (R-Ky.) on Tuesday sounded some of the most doubtful notes of Trump’s presidency that Republicans will keep the upper chamber of Congress, telling reporters, “I hope when the smoke clears, we’ll still have a majority.”

His comments came as Republican strategists and officials fretted over a fresh round of private polling on the Senate races, while public polls registered further erosion in Americans’ approval of Trump. “Shipwreck” was how one leading strategist described the situation, adding an expletive to underscore the severity of the party’s problems.

One of the most unexpected fights is in reliably GOP Texas, where Sen. Ted Cruz is trying to fend off Democratic Rep. Beto O’Rourke. Republicans are so fearful about losing the seat that they are diverting resources to Texas, a sore point in the White House after the animosity between Cruz and Trump in the 2016 Republican presidential primary.

Beyond Texas, Sen. Joe Donnelly, once seen as perhaps the most vulnerable Democratic incumbent, has opened up a slight edge over Republican businessman Mike Braun in Indiana, while hopes for picking off Sen. Joe Manchin III (D-W.Va.) in a state Trump won by 43 percentage points have faded along with GOP confidence in state Attorney General Patrick Morrisey, the Republican nominee.

The developments signaled the most serious peril yet for Republicans’ 51-49 majority. Losing the Senate was once an unthinkable prospect as the GOP looked to gain seats in the midterms, and with the party’s grip on the House in serious jeopardy, the chamber had been seen as the last line of defense.

At the start of Trump’s tenure, some Republicans envisioned enough wins to secure a filibuster-proof majority of 60 seats, confident they could oust many of the 10 Democrats running in states Trump won in 2016. Even a few weeks ago, Republicans were talking more assuredly about flipping seats.

But less than two months till the Nov. 6 election, Republicans barely mention Ohio, Wisconsin, Michigan and Pennsylvania — states Trump won — as opportunities to knock out a Democrat, while McConnell reiterated that nine seats, plus Texas, were at stake.

“Arizona, Nevada, Tennessee, Montana, North Dakota, Missouri, Indiana, West Virginia and Florida. All of them too close to call, and every one of them like a knife fight in an alley; I mean, just a brawl in every one of those places,” McConnell told reporters in Louisville.

Republicans could still emerge with an increase in their numbers if GOP candidates eventually prevail in many of these close races, with Democrats seriously concerned about Florida, where Republican Gov. Rick Scott is running about even against Democratic Sen. Bill Nelson.

The dire warnings also could serve as a wake-up call to GOP donors for the final eight weeks of the campaign.

But for the GOP, simply retaining its majority — which was whittled by a seat after a stunning upset in the Alabama special election last year — has looked like a more challenging goal by the day, as controversy swirls around Trump, the public loses confidence in the president and GOP candidates are slow to gain traction.

A Washington Post-ABC News national poll conducted in late August found just 38 percent of voters approved of the job that Trump was doing, compared with 60 percent who disapproved. His approval rating in April was 44 percent.

These difficulties have come into sharp focus in Texas, where Cruz is fighting for political survival against O’Rourke, a rising liberal star who is raising record-setting sums of cash and attracting large crowds across a ruby-red state. At the end of June, O’Rourke had close to $14 million cash on hand to Cruz’s $9 million, according to Federal Election Commission reports.

The tough realities of Texas have prompted an unexpected alliance between Cruz and the Republicans he spent years waging a vendetta against as a senator and as a candidate for president — including Trump and McConnell.

The sudden cooperation underscores how much the GOP fears losing Texas. The shock waves are being felt well beyond the state, as its several expensive media markets could force the party to spend money there that it will have to subtract from GOP hopefuls in other battlegrounds.

“Other campaigns are going to be shorted due to the lackluster nature of the campaign,” said one White House official, speaking of the Cruz operation.

McConnell recently assured Cruz in a private conversation that resources would be there for him, according to people familiar with the talk. Trump is planning to campaign for Cruz in Texas next month.

The Senate Leadership Fund, a super PAC helmed by a former top McConnell aide, has recently taken a close look at Texas, conducting polling and summarizing its findings in a memo, according to Chris Pack, a spokesman for the group.

The organization also announced a seven-figure advertising campaign in five other states on Tuesday. The ads mostly target Democratic candidates.

A Cruz-McConnell partnership would have been unimaginable when Cruz called McConnell a liar on the Senate floor in July 2015 over strategy on legislation. A Cruz-Trump alliance would have seemed equally implausible after Cruz labeled Trump a “pathological liar” and declined to endorse him at the Republican National Convention.

Beyond Trump and McConnell, Cruz angered other Republicans with his unsuccessful effort to strip funds from the Affordable Care Act in 2013, which forced a 16-day partial government shutdown, and his support for outside groups that financed primary challengers to GOP senators.

“They are working together for political expediency,” said Rick Tyler, a former Cruz spokesman. “These people don’t like each other.”

Cruz spoke about his plight at a luncheon for Republican senators earlier this summer, according to people familiar with his remarks. One GOP senator said Cruz sought to convince them that he was facing a“real race,” citing polls and noting that O’Rourke was amassing cash.

Like others interviewed for this story, the senator spoke on the condition of anonymity to describe private conversations.

In Texas on Tuesday, Cruz told reporters he was eager to debate O’Rourke five times. “Typically, sitting officeholders don’t suggest that many debates. They don’t want to do any debates. But the reason I proposed that is, I think we owe it to the voters of Texas.”

Sen. John Cornyn (R-Tex.), whom Cruz declined to endorse in his 2014 primary, is hosting a fundraiser for Cruz in Washington next month.

Public polls have shown Cruz leading O’Rourke by single digits. David McIntosh, the president of the Club for Growth, an anti-tax group that has long championed Cruz, said donors he has spoken with have been caught off-guard by the tightness of the contest.

“I think, particularly in Texas, it’s like: ‘Oh yeah, I didn’t think it would be a big race. Yes, we need to win it. I’ll help you do that.’ And the same around the country,” McIntosh said.

Speaking to reporters in Louisville on Tuesday, McConnell called the race “competitive” but said he expected Cruz to prevail. One advantage for any Republican in the state is the ability of voters to simply cast a straight-party-ticket ballot.

Despite Trump’s poll numbers, GOP strategists still consider the president their most effective weapon in the fight to keep control of the Senate. They say his trips to red states with marquee contests, like Montana, North Dakota, Missouri and Indiana, have provided boosts for their candidates.

The Senate Leadership Fund’s new Indiana ad begins with footage of Trump praising Braun and Braun pledging to fight for the president.

Whether the bursts of momentum will last is another question party leaders are grappling with as they eye the final two months before the November elections. A steady stream of explosive stories about dissent within Trump’s administration and special counsel Robert S. Mueller III’s investigation hover over the fall stretch.

Republican strategists are closely watching suburban areas, where they fear that anger with Trump could spark a backlash against GOP candidates. The suburbs loom larger over the battle for the House, with many rural states set to decide Senate contests. But Senate strategists are still mindful of the challenges they may pose.

One bright spot for the GOP has been the nomination of Judge Brett M. Kavanaugh to the Supreme Court. Republican leaders are confident they will confirm him this month, giving Trump and his party a landmark achievement just before voting begins.

Until then, they will have to weather a political storm that has increasingly stoked private GOP comparisons to 2006, a banner election year for the Democrats. Amid that perceived danger, every competitive Senate race is becoming more critical.